There is a growing body of evidence linking proinflammatory cytokines, including IL-10, IL-6 and TNF-cc to the pathophysiology of depression. The proposed K23 research study seeks to extend this line of investigation to pregnant women. Prenatal depression is common, affecting 10-15% of pregnant women, and has been linked with adverse outcomes for the mother and baby, including low birth weight, pre-eclampsia, premature labor and delivery and fetal growth restriction. Elevated levels of those same cytokines that are associated with depression in nonpregnant individuals, IL-1p, IL-6 and TNF-cc, have been implicated in premature labor and delivery, pre-eclampsia and premature rupture of membranes. This study aims to bring together two hitherto separate bodies of literature to examine the relationship between cytokines, depression and obstetric outcome in pregnant women. The specific aims are: 1) To test the relationship between depression and cytokine levels in pregnant and non-pregnant women. 2) To examine if there is an increase in cytokine levels from mid- to late- pregnancy in both depressed and non-depressed women, and if these intra-individual changes correspond with intra-individual changes in depressive symptomatology over the same period. 3) To test the hypothesis that cytokine levels and depression independently predict obstetric outcome. The study will comprise 64 pregnant and 64 non-pregnant women assessed at two time points, 18 and 32 weeks gestation. Each group will contain 32 depressed and 32 non-depressed subjects at Time 1;defined as a score of = 12 on the Edinburgh Postnatal Depression Scale and confirmed by SCID. At each time point, blood will be taken to measure levels of IL-1P, IL-6 and TNF-a;and data on depression and known risk factors for depression obtained;obstetric data will also be obtained. Maternal mental health is a public health concern due to the long-term effects on the mother, baby and family. Adverse obstetric outcomes including prematurity and fetal growth restriction are linked with perinatal deaths, or long-term physical and cognitive deficits in infants. Examining the link between cytokine levels, depression and obstetric outcomes may help to identify women at higher risk of adverse psychological and pregnancy outcomes.